Insecticide Sensory Detection in Malaria Vectors – INDEed

Insecticide-based vector control has been recognised as the principal contributor of the malaria-incidence reduction since 2000. Recently, this trend has worryingly stalled or even reversed in some countries. One identified reason of such stall is the evolution of insecticide resistances to the widely used pyrethroid insecticides in malaria vectors. Among them, behavioural resistance, i.e. behavioural modifications allowing to surpass the negative effects of insecticides, has been recently acknowledged but the mechanisms involved and their extent are nearly unknown.

The sensory detection of pyrethroids by mosquitoes has been proposed as a potential mechanism that could explain some forms of behavioural resistance. Although many studies have described a sensory-guided effect, such as repellency or irritancy, and some even attraction, nothing is known about how mosquitoes may detect and perceive insecticides. Ongoing behavioural experiments in our group have confirmed that on top of the already known irritancy effect through contact, it exists a spatial repellent effect of permethrin under certain conditions, yet the mechanisms are still to be described. On the other hand, the preliminary results of another experiment reveal for the first time that Anopheles mosquitoes are able to detect pyrethroid insecticides through their olfactory system. An olfactory receptor having permethrin, one of the most used insecticides in malaria vector control, as an agonist has been identified by heterologous expression. We have also carried out in vivo electrophysiological recordings from olfactory sensilla in the antennae, which confirmed the presence of specific olfactory sensory neuron responding to this pyrethroid. These results open the door to further investigate the role of the sensory detection of insecticides in mosquitoes, and not exclusively at an olfactory level, to reveal the functional roles that sensory receptors may have on their behaviour.

I propose an interdisciplinary project to study the neuroethology of Anopheles gambiae mosquitoes. Particularly, we will investigate the neurosensory mechanisms (i.e. olfactory, gustatory and nociceptive) of pyrethroid insecticides detection in malaria mosquitoes. Deciphering these mechanisms will allow us to study their implication on the behavioural modifications that may provide them with insecticide resistance, i.e. behavioural resistance.